The great majority of conventional boots incorporating a closure of this kind include boots whose shell is rigid or semi-rigid, e.g., "traditional entry" ski boots.
One conventional type of "traditional entry" ski boot, such as that described in FR 2 022 964, has a structure in which a shell base designed to receive the foot is surmounted by an upper intended to encase the lower leg. As disclosed, the shell base comprises an opening in the area corresponding to the instep/flection fold, and a tongue which seals this opening and originates at the tip of the boot. This tongue extends into the flection fold area and is advantageously connected to the edges of the opening using flexible segments which form a watertight bellows. This construction is a definite improvement as compared with "free" tongues, i.e., those which are merely attached or originate at the tip of the boot. In fact, because of the geometry of conventional tongues, which separates them distinctly from the front part of the upper (shell base), they cannot really provide water-tightness of the boot. Accordingly, it is desirable for the edges of the tongues to be attached to the edges of the opening in the shell base, as in the example represented by FR 2 022 964. It will be noted that the use of this means of providing water-tightness, which is molded in a single piece with the boot upper, proves relatively easy to incorporate into this type of construction, since there is really no edge-to-edge superposition of the tongue in conjunction with the edges of the upper placed opposite each other. Furthermore, as acted upon by the lace-tightening device, the tongue is pressed down principally on the top of the foot while also pushing the water-tightness element back against the latter. It is the tightening device which tends to draw the edges of the opening closer together. Pressure exerted on the tongue thus does not cause these edges to move closer together.
Another type of "traditional entry" ski boot, described in Patent No. DE 1 904 847, comprises a shell base designed to house the foot, this shell base being equipped with a walking sole and surmounted by an upper designed to encase the lower leg. As taught and illustrated, the shell base at least is open at the top in the area corresponding to the instep/flection fold. This opening extends along the longitudinal axis of the boot and exists as a slot delimited by the overlapping of an exterior transverse flap originating on one of the sides of the shell base over an interior transverse flap originating on the opposite side of the shell base. Depending on the structure of the tightening device used to apply pressure to the exterior flap positioned over the interior flap, these flaps are sized so as to cover the instep area and up to the area of the front part of the foot adjoining the toes, i.e., the tip of the boot. Seen laterally, the entry to this slot is given material form by the position of the free end edge of the exterior flap in relation to the wall opposite the interior flap, and it thus extends, lengthwise, at a distance relatively close to the median longitudinal axis of the boot, and, widthwise, on the front portions of the flaps, which are superposed transversely to this longitudinal axis while projecting at least partially from the top of the boot tip by their respective narrow edges. The water-tightness of the closure for this type of ski boot is obtained laterally by pressing the exterior tongue on the interior tongue and, according to the improvement introduced by the invention, by the addition of a bellows-type jointing element positioned on the front part of the slot in proximity to the tip of the boot and in conjunction with the transverse ends of the projecting flaps. This jointing element, or bellows, is arranged inside the shell base and is connected in an edge-to-edge configuration to the edges of the flaps, solely in the area of the boot tip. As designed, when closure is effected, the bellows folds back on itself, and any movement bringing the exterior and interior flaps closer together from that closure position tends to stretch the bellows. It will also be noted that, since the bellows is positioned inside the shell base, the opening of the boot by drawing the flaps apart (putting on or taking off the boot) exposes the bellows and thus makes possible, during this operation, the penetration of snow, gravel, etc. between the bellows and the flaps to which it is attached.